BuildWorld is a multi-player online game.
The BuildNetwork is a network in which players can interact with each-other, going to player's worlds. Is it also how to get to multi-player.
Each world has colors for each rank.
Mini-Admin: Light Blue
Here are the requirements to become a rank.
Member: Play for 5 hours.
Builder: Build something and have an admin view it and rate it.
Mini-Admin: Help admins.
Admin: Have a Co-Owner approve you as an Admin.
Co-Owner: Have the Owner approve you as a Co-Owner.
Owner: Create the world.
To change the colors, you must be an Admin, Co-Owner or Owner. You have to go to the Admin's Menu. Then, click the "Colors" button. Then you will see a color slider. Slide the crosshair to the color you want and click "Save", and then "Quit".
Worlds are places you create, you can play Single-Player or Multi-Player in them.